1. Field of the Invention
The present invention relates to a method of fabricating macroporous carbon capsules, and particularly, to a method of fabricating macroporous carbon capsules from a natural source.
2. Description of the Related Art
Porous carbon materials are utilized for various applications, including drug delivery agents, heat-insulating materials, buffer materials, pollutant absorbent materials and catalyst carriers.
Several plant parts, such as wood, leaves, fruit, and spores have a polymeric structure consisting of carbohydrates (cellulose and hemicellulose) lignin, intine and sporopollenin with small amounts of extraneous organic chemicals and minerals. Carbonization of plant residue can give rise to a solid mainly composed of carbon atoms, heteroatoms (mainly hydrogen and oxygen), and a mineral matter usually provided as ash. Such a solid can be wood charcoal. Pyrolysis of lignocellulosic materials generally produces char, tar, volatile liquids and gases. The volatile materials are lost during the wood carbonization process and form a carbon skeleton and a rudimentary pore structure. The residual elementary carbon atoms, visualized as stacks of flat aromatic sheets, are cross-linked in a random manner, leaving interstices which may become filled with tars and other decomposition products or at least partially blocked by the disorganized carbon. The surface of non-graphitized carbons, such as wood charcoals, consists of graphene sheets and edges of such layers, with heteroatoms, in particular oxygen, which is predominantly located on the edges in the form of various functional groups.
A macroporous material formed from a carbon material has high electric conductivity, lightness in weight, heat resistance, chemical resistance and the like, which other macroporous materials do not possess. Accordingly, a macroporous carbon material has wide-ranging applications for heat-insulating materials, heat exchangers, filters, ceramic sintering tools, glass shaping tools, various electrodes for fuel cells, special adsorbents, various catalyst carriers, filters for vapor filtration, etc.
Thus, a method of fabricating macroporous carbon capsules from pollen grains solving the aforementioned problems is desired.